The present invention relates to an electrical flex circuit, and more particularly to a flex circuit comprising a lattice area with reduced bending and torsional stiffness and reduced thermal expansion properties.
Electrical flex circuits or cables are typically made of copper sheets deposited on a flexible carrier, such as a polymeric sheet. Portions of the copper sheet are masked with a desired pattern. The masked portions are etched to leave the desired pattern in the copper in the form of conductor traces. The pattern corresponds to a particular electrical circuit.
The stiffness of the polymeric sheet and of the copper determine the stiffness of the flex circuit. A desire to reduce or eliminate the torsional and bending stiffness of the flex circuit has led to a search for a super soft carrier or thin material to reduce the stiffness of the entire flex circuit. However, reducing the stiffness leads to a degradation of the flatness of the flex circuit. Also, the polymeric material used to construct the flex circuit is sensitive to temperature fluctuations. Temperature fluctuations can therefore cause undesirable thermal expansion and contraction in the flex circuit.
As a result, typical flex circuits have limited applicability in certain applications, such as in the electrical connections of a head gimbal assembly (HGA) of a disc drive data storage system. The head gimbal assembly is supported by an actuator assembly and includes a disc head slider and a gimbal. The slider carries a transducer for communicating with a recording surface in the storage system. The gimbal provides a resilient connection between the actuator assembly and the slider which allows the slider to pitch and roll while following the topography of the recording surface. The stiffness of traditional flex circuits have limited the applicability of flex circuits between the actuator assembly and the transducer since the stiffness interferes with the pitching and rolling of the slider and thereby adversely affects the flying characteristics of the slider.